What Car?’s technicians drive new cars every week to capture our True MPG fuel economy data. Unlike official Government figures generated by a laboratory test, the numbers we publish are gained from real-world conditions.

This week we’re taking a look at the most economical two-door coupes we’ve tested so far. There’s a mixture of manual and automatic gearboxes, but all six are diesel-powered. These cars are stylish and efficient, as all beat 45mpg in our test.

1. BMW 220d Coupe – official 62.8mpg, True MPG 55.8mpg

The most efficient coupe in this round-up is also the smallest. The new 2 Series has plenty of space for two adults in the front, but there’s really not much room in the back. In 220d SE guise it has plenty of power and equipment, although the engine is very grumbly at low speeds. Still, if you can live with that – and treat it as a two-seater – this coupe is classy, comfortable and fun to drive.

2. BMW 420d Coupe – official 60.1mpg, True MPG 52.5mpg

The 4 Series is lower and wider than the 3 Series saloon, which improves the already impressive ride and handling – as long as you add the optional adaptive suspension. As in the 2 Series, the 2.0-litre diesel sounds a bit gruff, but this coupe will transport four adults in comfort and it’s loaded with standard kit, including heated leather seats and xenon headlights.

In the A5, Audi is only offering the 2.0 TDI Ultra in SE trim with a manual gearbox. The specification level is generous including Bluetooth, multi-zone climate control and heated leather seats. The only option we'd recommend selecting is the £1695 Technology Pack that adds sat-nav. The A5 is refined but some drivers may find the off-set pedals uncomfortable.

4. Mercedes E220 CDI Coupe – official 58.9mpg, True MPG 49.7mpg

We’d recommend going for the E220 in entry-level SE trim, as AMG Sport models have suspension that is slightly too firm. You won’t be short-changed on equipment either; SE cars get an online sat-nav system, DAB radio and a system that helps you park by controlling all the steering inputs.

The Scirocco is one of the more practical coupes you can buy, but is still sleeker and sportier than most hatchbacks. The Bluemotion Tech model is the most economical version in the range, and still offers decent performance.

6. BMW 640d Coupe – official 51.4mpg, True MPG 45.2mpg

The 6 Series Coupe is fast, refined and, with this pick-of-the-range engine, efficient. While the rear seats are best left for children, the boot will easily accommodate a couple of suitcases or golf bags. The optional adaptive suspension doesn’t completely remove the firm edge to the low-speed ride, but this is still a great grand tourer.

We add new models to our True MPG database every week. Visit whatcar.com/truempg to see the full range of cars we’ve tested, and find out what you really can expect to achieve on UK roads.